Heating apparatus



March 2, 1965 F. GANZ HEATING APPARATUS 4 Sheets-Sheet 1 Filed May 9, 1963 Ti:|.2. G

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United States Patent G 3,171,388 HEATING APPARATUS Felix Ganz, Lucerne, Switzerland, assignor to Ygnis SA., Fribourg, Switzerland, a stock company of Switzerland Filed May 9, 1963, Ser. No. 279,048 Claims priority, applicatosnsvitzerland, Oct. 10, 1956, 1s claims. (0.12%149) The present application is a continuation-impart of application Serial Number 691,117 tiled October 7, 1957, entitled Method of Burning Fluid Fuels and Heater for Utilizing Such Method.

This invention relates to furnaces in general. It is concerned particularly with a water heating boiler for providing hot water or steam to the heating systems of buildings.

A water heating boiler when red by an oil or gas burner injects the fluid fuel together with a flow of air under pressure into a re box having a water jacket which surrounds the lire box with the water to be heated. The lire box is made of metal such as steel or iron. Where the ame from the burner impinges on the fire box directly, nonmetallic refractory elements are used which, when heated adequately, tend to promote more thorough burning of the fuel while serving to protect the metal from the flame.

When the tire box has a cylindrical contour, the prior art teaches that the burner should be located on the axis of the iire box so that the llame contour substantially coincides with the shape of the fire box and is kept from direct impingement therewith excepting at the end of the tire box remote from the burner where the nonmetallic refractory is placed to assist in obtaining more complete combustion and so as to protect that end of the tire box against direct flame impingement. A number of exhaust dues may be arranged as an arcuate series arranged concentrically with respect to the cylindrical side wall of the re box with entrances connecting with the latter adjacent to its burner and with these flues extending through the Water space formed by the water jacket, the ilues having exhaust exists adapted for connection with a stack or chimney.

The above has the disadvantage that even with the use of the nonmetallic refractory for assisting the combustion of the fuel, incomplete combustion is not unusual. The nonmetallic refractory is expensive to install and it forms undersired thermal insulation between the flame and the wall of the combustion chamber, this interfering with the transfer of heat from the flame and its resulting hot gases to the water surrounding the tire box. Particularly when made large enough to have the capacity required for heating large buildings, there is a problem in getting the flue gases up the stack or chimney into the atmosphere, ordinarily solved expensively by providing a large capacity stack or flue or resorting to the use of a mechanically forced draft requiring blowers or fans. In spite of the described precautions the fire box may be subjected to hot spots resulting in premature iire box failure. Because the heating efficiency is undesirably low the physical size of such a conventional water heating boiler must be made undesirably large as related to the heating capacity obtained.

The object of the present invention is to provide an improved heating apparatus the principles of which are particularly applicable to a water heating boiler when fired by an oil or gas burner of the previously described kind, although these principles may be applied otherwise. More speciiically, it is desired to eliminate the need for the nonmetallic refractory used usually, to permit the use of a stack or chimney of reduced size as compared to that required conventionally and Without using mechanical forced draft expedients, to reduce the problem of hot spots forming in the lire box and to provide for an increased eiiiciency permitting a reduction in the physical size of a water heating boiler as compared to the size of the conventional boiler of corresponding heating capacity.

A heating apparatus made in accordance with the present invention features an enclosure or lire box formed by a substantially cylindrical side wall and interspaced end front and back walls. The front wall may be a door providing internal access for the removal of soot, for example. Means are provided for introducing a flow of hot gas in the enclosure flowing backwardly from the front wall mainly on one side of the axis of the side wall and which is looped forwardly by the back wall to then flow forwardly mainly on the opposite side of the side walls axis towards the front wall of the enclosure or lire box. Fines are provided for exhausting the hot gas at or adjacent to the front wall.

Further, the exhausting means is constructed with a flow capacity choking the exhaust ilow therethrough. This causes the atmospheric pressure within the enclosure or fire box to increase because of the introduction of the flow of hot gas.

Two particularly desirable effects result from the foregoing principles. One is that the gas after being looped forwardly and while flowing forwardly does not all exhaust through the exhausting means but instead loops a second time, Ithis time in a backward direction, so as to rejoin the hot gases being introduced. When the hot gas introducing means is in the form of a fluid fuel burner using air under pressure of theoretically the proper amount for complete combustion, although complete combustion might not ordinarily occur prior to exhausting to the stack, the hot gases and unburned fuel and air in this case are reintroduced to the hottest part of the flame, thereby promoting complete combustion without using the customary nonmetallic refractory elements for this purpose. The other advantage is that the lire box may be operated at superatmospheric pressure so that the ue gases exhaust under this pressure so as to travel to the outer atmosphere even though a smaller than usual stack or chimney is provided.

Because the re box of this invention proivdes for a whirling substantially closed loop of flame and hot gases within the fire box the danger of hot spots is reduced or eliminated. Rapid heat exchange between the llame and hot gases and the tire box is promoted. There is no need for the undesirable thermal insulating effect necessarily incidental to the use of nonmetallic refractory elements. The cost of such elements is eliminated.

ln this invention the fluid fuel burner location departs from concentricity with the axis of the cylindrical side Wall of the fire box which is the obvious location because it is what is taught by the prior art literature and engineering practices. Instead, the burner is installed through the front end wall of the enclosure or iire box at a location between the latters axis and its periphery. In other words, this location is offset from this axis. The degree or distance of this oifset may be Varied but as a minimum it should be sufficient to assure that the llame is introduced mainly on one side of the axis of the enclosure or fire box. The oifset must be sufficient to provide room on the other side of the axis for the return or forward flow resulting when the injected llame and hot gases are looped forwardly by the back end Wall.

The flow resistance to the whirling loop of flame and hot gases maintained within the fire box is reduced by making one or both of the two end walls more or less concave internally. With the front end wall, which may be the door, having at least a portion that is concave the fire boxs interior may use this concave portion as a passageway to the entrances tothe ffues described previously. In such an instancevthe door may be made hollow and water cooled in Vthe customary manner and the water used may be part of the body of Water maintained in the waterY jacket around the fire box so as toy prevent heat loss. Otherwise, such as in the case of smaller units, the door may be solid and made with a suitable refractory interior. Specific examples of water heating boilers embodying the foregoing and other principles of the present invention are villustrated by the'accompanying drawings in which:

FIG. 1 is` -a vertical' cross `section taken on the line 1 1 inFIG.2;V Y FIG. 2 is a longitudinal section of a first example of the water boiler; f FIG. 3 is a longitudinal section on enlarged scale showing the entrance to one of the flues;

FIG. 4'is an end elevation of a second example with the door or front end wall removed;

FIG. 5 is a longitudinal section taken on a vertical plane of the example shown by FIG. 4; Y FIG. 6 -is a partially broken away back end View of the second example; Y t Y FIG. '7 showsl partly in elevation and partly in transverse cross sectionthe water inlet to the water boiler forming this second example;

FIG. 8 is a longitudinal showing a third example; l v

FIG. 9 shows partlyV in elevationand partly in longitudinal section taken on a vertical plane, a commercial form of the present invention; and

FIG. 10 is a front view partly in elevation andpartly in cross section of the form shown by FIG. 9.-

section taken on a vertical plane Of these drawings, FIGS. 1/-8 are somewhat schematic.V

They are intended to illustrate the fundamental principles of the invention.Y

Y radially from this axis.

Vwater jacket. -with thebackwardly projecting fire box forming ineffect 2a of the fire box is shown by a broken line marked X-X. It can be seen that the burner tube BT is located substantially entirely below or practically completely offset The port 4 is, of course, located correspondingly as must be theburner, mounted to the door, providingthe burner tube.

lAs previously indicated, the distance the burner isroffset from Vthe axis of the cylindrical'side wall of the fire box'fmay be varied providing the previously described effectis achieved.V According to the prior art the burner should be located so as to inject itsflarne into the re box as exactly at thevaxis as manufacturing precision makes possible. To achieve the action o f the present invention the burner must be offset definitely from this axis a distance sucient to make sure that the main portion ora majority of 'the .fiarneand the resulting hot gases flow through the fire box'on one side of the centerline of the fire'boxs cylindrical side wall 2a, then loop forwardly by deflection caused by the concave inner surface of the fire boxs end back wall 2b, and then to flow forwardly on the opposite side of the axis from that where the backward flow occurs. The location of the burner should be such as to avoidthe flame and hot gases impinging the back end wall 2b substantially centrally so as to more or less uniformly fan out in all radial directions. 'Such an action would require the use of nonmetallic refractory elements for protecting the end back walland to maintain ignition of the fuel.

Although the front end of the' fire box is interconnected in a substantially rigid manner with the corresponding end of the water jacket W as previously described, the rest of the fire box is free to expand and contract. In effect, the rest ofthe fire box floats within the Water confined by the This freedom to expand and to contract a cantilever, need notV be interfered with even though the Referring first to FIGS. l-3 in this first example the Y combustion chamberspace 1 is defined bythe fire box'z which has a cylindrical side wall 2a, which is considerably longer than its diameter, and a back end wall 2b that is concavo-convex with its concave side facingrrinward-ly.

This fire box 2 may follow the usual practice insofar assit is made from a suitable metal in the form of a shell having the back end wall which is generally do-mevshaped so as to form a cuplike structure. The fire box may be made from steel or iron and its wall thickness neednot be very great as compared to itsl lateral extent. The fire box interior does not contain any nonmetallic refractory element or the like at or adjacent to the end wall 2b. The fire boxs inside surface is entirely open to the flame and hot gases.

This fire box Z'Vis surrounded by `a water'jacket W and the fire box connects with the water jacket at the front end of the fire box by wall members 2c which extend in a generally radial direction outwardly so as tojoin with the outer wall of the water jacket, the latters inner wall being the fire box itself. The front of the fire box 2 is fire box `is additionally supported. For example, the cylindrical-side wall of the fireV box may be supported by a pedestal 5 of downwardly spreading Vsshaped cross sectional Ycontour which bears on thebotto-m wall of the water jacket W which is in turn supported by base member `6. However, the pedestal should have a freely movable relationship with respect to the bottom wall of the water jacket W so that the fire box remains free to expand and contract throughout itsV portions not connected to the water jacket. Such expansion and Vcontraction'mayrbe caused by thermal influences.

The cold water returning to the furnace from the heat- Y ing system for reheating, enters the waterjacket through closed by a door 3 which provides the front end wallof the combustion chamber 1; This door may be solid or hollow and water cooled.

Like the examples described hereinafter, thepresent example is a water'boiler heater of the horizontal type. The lower portion of the door 3 is provided with a port 4 ad/apted to receive the burner tube BT of an oil or gas burner of the type provided with a blower for providing aV The burner -shouldbe tted to Vthe port so as to prevent the escape of gasesfrom the combustion chamber. Y The burner ftube BT is indicated schematically by broken lines in FIG. 2, and the axis of the cylindrical side wall an inlet7 with the flow going between the two legs of the Vpedestal 5.- V'Ihese two legs, in theforrn of elongated plates, are provided .with a series of holes 8 formed through them transversely so that the water enters the lower portion of the water jacket from these holes. This introducesV agwhirling Vaction to the water promoting the heat transfer between the outside of the fire box 2 and the water. The flow of Ywater circumferentially'around the yfire boxV keeps the Water in the Water jacket moving at all times. f

Thefront end of the Yfire box 2 Vis shaped to form an upstanding Ydome 9 Vand two generallyarcuate series of fines 10 have their entrances connected with or opening'from this dome 9. The two ser-ies are superimposed radially with respect to the axis'of the fire box 2. These fluesV extendlongitudinally backwardly from the dorne 9 through the water space formed by the water jacket W. The back ends of the fluesspass through the Wall of the water jacket so as to open into an economi/2er 11. Some vrofthe Vcold water'returning from the heating system may brazed to the vertical wall of the dome 9 and to the tube 10 in each instance as shown by FIG. 3. These connections 13 are in the form of flaring members which reduce the flow resistance while having the further advantage that when a flue, which is in the form of a tube, has to be changed the necessary separation and subsequent rejoining may be effected at the points of the welds or brazes of the connections 13 without damaging the adjacent portions of the wall of the fire dome.

As previously indicated, the overall or total fiow capacity of the fllue tubes 10 are related to the volume of the hot gas created in the fire box by the burner tube BT so as to cause the atmospheric pressure in the fire box to be maintained higher than atmospheric pressure. In the commercial form of the device the iiue gas pressure does not drop to atmospheric pressure until the fine gas exits from the fiue tubes.

The return or forward flow of the looped hot gases does not all escape through the flue tubes. These forwardly flowing gases, normally containing a substantial amount of unburned fuel, loop backwardly or reversely adjacent to the front end wall or door 3 so as to rejoin the flow created by the fiame injected into the fire box by the burner tube BT.

The result of the o center burner tube location possibly aided by the above is the whirling loop of flame the path of which is indicated schematically by broken lines and arrowheads in FIG. 2. The entire fire box is filled substantially uniformly with this whirling closed loop of fiame and hot gases. Because of the recirculation there is adequate time for complete combustion and reignition when necessary is constantly effected by the fiame injected by the burner tube BT. Because of the flame motion the metal wall of the enclosure 2 is constantly wiped by the fiame and hot gases with the temperatures existing within the various zones of the fire box 2 remaining relatively constant as compared to prior art furnaces.

The need for nonmetallic refractory elements is eliminated because their normal function of maintaining ignition by being heated to incandescence is supplied by the reintroduction of the fiow to the burners flame just beyond or leaving the burner tube. The need for such refractory elements to prevent direct flame impingement is eliminated because the whirl-ing loop of flame has approximately a constant temperature throughout the interior of the fire box 2. Instead of impinging directly against the concave inside of the fire boxs back end wall, the flame rotates or turns at this point as it is not only forced forwardly by its looping action, but drawn in that direction by the action of the flame injected by the burner. The relatively high pressure within the fire box keeps the ame from concentrating locally at any place.

In effect the flame assumes an elongated egg shaped pattern of continuously moving fiarne, hot gases and unburned fuel particles or gases. This fiame pattern is continuously kept in motion by the action of the injected ame. The arrows and broken lines shown in FiG. 2 represent to some extent the pattern formed by the unburned fuel, particularly in the case of oil. The entire fire box is filled with the fiame and hot gases.

All of the tiue tubes are connected through the economizer 1l with a common exhaust port or duct which may be connected to the stack or chimney. Because of the pressure existing in the fire box the stack gases need not be sucked from the fire box, thereby eliminating the need for an expensive large size stack or chimney or mechanical forced draft expedients.

Practical experience with the commercial form of the furnace has shown that when burning heavy grades of furnace oil little soot or coke is found in the enclosure 2. This indicates the practically complete combustion obtained even though the usual nonmetallic refractory elements normally provided to maintain ignition and promote combustion, are not used.

Since the flue tubes 19 pass through the water in the water jacket, a large amount of the ue heat is recovered directly. To prevent laminar flow through these tubes flow agitation members may be used such as helical wire elements indicated at 14. Due to the efficiency of this heat recovery economizer il may at some times present the disadvantage that the existing flue gases are so cold as to drop to a temperature below their dew point temperature. Then the economizer need not be used.

In the example shown by FIGS. 4-7, the parts that correspond with the parts of the first example are given corresponding numerals. The difference is that the door 3a is formed with an interior surface that includes an inwardly facing concave portion l5. This eliminates the need for the dome 9 of the first example. The fire box 2 extends fully forwardly and joins with the water jacket W by way of a radially extending wall portion 15a and the entrances to the iiues 1Q open into this wall portion. The concave portion 15 of the door extends radially far enough to overlap the entrance to the tubes 10 and thereby form a passageway leading to these tubes.

As shown by FIG. 4 only a single arcuate series of interspaced flue tubes i@ is provided. In this series the tubes are arranged to form a pattern that is a segment of a cylinder which is substantially concentric with respect to the axis of the fire box 2. It follows that the concave portion l5 can be made more extensive and so as to embrace the entire inside of the door 3 to provide an internal cavity generally corresponding to that of the back end wall of the r'ire box but having an adequately large radius to overlap the entrances to the flue tubes. Correspondingly, the arcuate series of liuc tubes can be extended until a circular series is formed which completely surround the fire box. ln such a case the individual inside diameter of each fiue tube is proportioned so that the total flow capacity of all the tubes as related to the capacity of the burner, may be adjusted to maintain the superatmospheric pressure within the fire box and fine tubes. With a larger number of flue tubes a larger burner may be used.

In this second example, the pre-heated water from the economizer is injected into thc water jacket `W by a tangential inlet 16 so as to obtain a whirling action of the water for the purpose described previously. If the economizer is eliminated the cold water returned from the heating system may be introduced to the water jacket through this inlet 16.

As in the first example, only the front end of the fire box 2 is rigidly connected to the water jacket, the re box more or less functioning as a cantilever within the water jacket. As additional support the fire box has a rear extension i7 which is supported loosely on a member 18 connected to the water jacket.

in this second example the door is more directly affected by the hot gases within the furnace and, therefore, it may be water cooled. Conveniently this is done by making the door hollow and connecting its interior through fiexible connections with the water in the water jacket, this not only preventing overheating of the door but preventing loss of heat by exchanging it with the water.

In all of the examples described hereinbefore the burner has been shown as being located below the axis of the cylindrical side wall of the tire box. The new operation can be obtained regardless of the location of the burner providing that it is offset from the axis of the cylindrical side wall of the fire box 2 enough to cause the injected flame and hot gases to travel backwardly into the fire box mainly on one side of the latters axis and to then move forwardly and fiow forwardly mainly on the other side of this axis. Then the forwardly traveling flame and hot gases rejoin with the ame injected into the furnace. It follows that the burner could be located above the axis or horizontally offset from the axis and the principle of operation could be applied to a vertically arranged fire box and water jacket if desired providing the offsetting of ythe burner is effected to an adequate'rdegree. TheV prin-V ciple of operation described hereinabove might be applied even to a coal burning furnace providing an adequate blast of hot air is furnished over the grate so as to obtain the closed looped whirling action of the hot gases.

Experience with prior art furnaces burning oil have shown that the heated surfaces are sooted to a high degree and that sulphur may be deposited so as to promote corrosion trouble. This has led to suggestions that some of the waste gases should be returned to the burner directly at the source of the ame so that the'fine soot particles of the hot gas produced by the ame can combinewith the sulphur compounds and reduce the trouble.

With the above in mind, in the example or modification shown by FIG. 8 the burner tube 19 of the oil burner is inserted through the port 4 in the door 3 the latter being.

either made with a nonmetallic refractory or made hollow and adequately water cooled as previously described.` T he burner port is made with a funnel-shaped enlargement which is located in front of the tube 19 and a funnel 21 is made of suitable refractory and located in the enlargement Zt in spaced relation therewith. This part 21 therefore leaves space through which a portion of the hot gases present in the combustion chamber l formed by the lire box 2, is conducted. This may be either because ofthe excess pressure in the fire box or by an aspiration action produced by operation of the iarne in the vicinity of the ports 23. v

In the above-fashion a portion of the hot gases is drawn directly to the burner for reintroduction tothe furnace, as shown by the arrow diagram in FTG. 8. The amount of-waste gases or other atmosphere from within the fire box thus introduced to the source of the flame may be regulated by axially movingY the vburner tube i9 in any suitable manner.

The foregoing is substantiallyv the same disclosure as was in the original application Serial Numberk 691,117.

The commercialized form of the invention is shown by FIGS. 9 and l0 and the transition from the original forms.

of the invention to this commercial form are apparent;

Referring now to FIGS. 9 and l0, the 'combustion chamber is formed by the fire box having the cylindrical side wall 31 and, while only partly shown, the concavoconvex back wall 32 previously described. Thisre box is made of metal with a smooth interior and is free from.

any interior nonmetallic refractory elements. VThe water jacket 33 encloses the tire box in the form of a second cylinder concentric with the cylindrical side wall 31 of the tire box and a back wall 34 that follows generally the contour of the end back wall 32. of the tire box. ln other words, there are interspaced inner and outer cylindrical side walls and inner and outer concavo-convex end walls both formed from metal ofV about the same thickness that is used by prior art Water heating boilers. Y

The front end of the lire boxs cylindrical wall 31 has a radial wall 32 which is a common wallrwith respect to the water jacket and which interconnects the two rigidly. The rest of the re box extends into the water from this Wall 32 in the form of a cantilever. 'Therefore, the

' fire box is entirely free .to contract and expandasV required. The door is formed by an outer wall 35 and an inner wall 36 having a completely concave inside. The

door is sufficiently greater in diameter than the diameter of the fire box to overlap the wall 32 a substantial amount.

vThe interior of thisdoor is hollow to form/a water-cooled from the water space. Both tubes 37 and 40 connect with or open into thewater space between the doors walls 35 and 36.

Note that the concave inside 36 of the door corresponds to the concave section 15 shown by FIG. 5, excepting that now there is Vcomplete concavity throughout thedoor. The iiue tubes 37 in this form are, therefore. made as a completely circular series surrounding completely the firev boxs wallY 31 and substantially concentric therewith. The inlets or entrances to these flue tubes receive the waste gases by way of the peripheral passage formed by the concavity ofV the doors inner` wall 36 and they exhaust into a manifold 38a which connects them with a common stack or chimney connection 39a. Eachtube 37 contains a helical wire flow turbulating member 4t) which may be pulled forwardly from the tube in each instance when the door is opened. i

The burner port 4l is shown as being located almost completely offset from the axis of thecylindrical side Wall of the re box. The latter has a length approximately twice its diameter and in any event this length should be substantially longer than the diameter of the rire boxs side wall. .The port 41 is, of course, adapted to receive the burner tube of a standard oil burner having a blower or fan for injecting the air under pressurejand usually the oil is injected under pressure. A flange 42 serves to mount the oil or gas burner unit on the door and the latter closes `gas-tightly by reason of aseal 43 on the door frame. ,i p l Although not previously mentioned in the preceding examples, a case or protective or decorative covering 44 encloses thewater jacket and inthe case of the cornmercial form this water jacket casing or protector 44 is shown. This may have a rectangular shape and it may encaseA thermal insulation surrounding the water jacket.

vWith the door provided with the substantially gas-tight seal 43, the burner installed to thel door may have adequate capacity so that'the circular series of flue tubes 37 exert Ya choking` actionA and produce the superatmospheric pressure within the combustion chamber.V Because of the circular side wall and the concave 'surface ofthe end back` wall and the end front wall, provided by the door, together with the axiallyoffsetrelationshipV of the port 41, the whirling mass of flame and hot gases is produced.

' Vfhe Vflow is inthe Vform of a closed loop or egg-shaped mass of hot llame land hot gases following closely all of the inside surfaces ofvr the combustion chamber. Exhaust is effected around the entire periphery of this flame by way of the annular series V.of flue tubes 37. The latter give up rsome of the'y heat of the ue gas to the water confined by the water jacket around the fire box.y

One closed loop would not ordinarily provide for com'- plete combustion of the oil but the unburned oil is reintroduced to the oilA burners flame at the end of the first looped circuit and continuously thereafter. There is no* chance forthe flame to lose ignition heat because it is continuously reintroduced to the oil burners flame.

VConventional oil burners introduce a relatively high velocity ame so the velocity of the whirling closed loop of'hot frame and gases existing within theA fire box has relatively high velocity. The entire inner surface of Y For equal heating capacity the water heating boiler Y shown by FIGS. 9 and l0 when compared to prior art vboilers of comparable lheating capacity, requireV sublatter connecting with the water space between the Vfire boxs Walls and the water jackets Walls. upper portion of the door connects through a flexible tube 4t) with the boilers output connection 41 which leads The top or Y stantiallyy a smaller amount of space.V Any stack or chimney to which.the iiue gas outlet 39 is connected `receives `the gas, under at least some pressure above atmospheric or at least .at atmospheric pressure and obtains the advantages previously described. Although the formation ofV soot and'car'bon is largely avoided, clean-V ing of the iire box is effected `easily by opening the door.

The fire box is entirely free from lire brick or other nonmetallic refractory elements such as are usually required to maintain ignition and protect the metal re box against direct llame impingement. Opening of the door exposes all of the llue tubes so that the wire elements 37 may be pulled out for cleaning.

The heat recovery effected by reason of the circular series of flue tubes extending directly through the water is so eiicient that no economizer is needed. As previously indicated, an economizer might result in an undesired excessive drop in the temperature of the exhausting flue gas.

It can be seen -that the main difference between the commercial form and the originally disclosed forms of the present invention is the extension of the concavity shown by FlG. 5 so as to make this concavity embrace the entire door, and the extension of the partly circular series of flue tubes shown originally, to form a completely circular series. The transition of the first form to the present commercial form has involved no departures and this commercial form is now in extensive successful use commercially.

The water jacket at its back end may be supported by a saddle 45 mounted by legs 45. This may be done loosely to permit expansion and contraction, the water jacket otherwise being supported only at its front end by the case 44 which may be made structurally strong for this purpose. Although not shown, the lire box may be supported at its back end loosely as described before. When the water jacket is empty this support of the fire box may be desirable.

What is claimed is:

1. A fluid heater including a fire box formed by a substantially cylindrical shell having a length greater than its diameter and having an end back wall, a closure forming an end front wall for said enclosure, fluid fuel burner means mounted through said closure at a location between the axis of said shell and its periphery and directing a liow of burning fluid fuel and gas flowing backwardly towards said back wall mainly on one side of this axis and which is looped forwardly from the back wall and flows forwardly mainly on the opposite side of this axis, a jacket enclosure for said shell and its back wall for surrounding the latter and the shell with the uid to be heated, and ue means having an entrance at least adjacent to said end front wall and communicating with the shells interior and having an exhaust exit for connection with the outer atmosphere, the total flow capacity of said flue means being related to the capacity of said burner to Vform hot gases from said burning lluid fuel within said lire box, to maintain a superatmospheric pressure within the re box.

2. In a furnace, in combination, an elongated cylindrical combustion chamber having a horizontal longitudinal axis and two end walls extending transversely of said axis; a shell surrounding said combustion chamber and forming a water jacket therewith; burner means cornmunicating with said combustion chamber at one of the end walls thereof at a part of said one end wall spaced from said axis for projecting a flame into said combustion chamber longitudinally thereof, said burner means during operation providing an endless stream of combustion materials circulating in said chamber; and a fire tube in said water jacket extending parallel to said axis and communicating with said combus-tion chamber adjacent said one end wall thereof at a part spaced from said burner means on the side of said axis opposite `from said burner means, said tube providing restricted outlet means for discharging only a portion of said combustion materials from said stream out of said chamber, whereby another portion of said materials returns to said stream, said furnace further including a base member, a support member movable on said base member, said combustion chamber being mounted on said support member.

3. In a furnace, in combination, an elongated cylindrical combustion chamber having a horizontal longitudinal axis and two end walls extending transversely of said axis; a shell surrounding said combustion chamber and forming a water jacket therewith; burner means communicating with said combustion chamber at one of the end walls thereof .at a part of said one end wall spaced from said axis for projecting a llame into said combustion chamber longitudinally thereof, said burner means during operation providing an endless stream of combustion materials circulating in said chamber; and a lire tube in said water jacket extending parallel to said axis and communicating with said combustion chamber adjacent said one end wall thereof at a part spaced from said burner means on the side of said axis opposite from said burner means, said tube providing restricted outlet means for discharging only a portion of said combustion materials from said stream out of said chamber, whereby another portion of said materials returns to said stream, said furnace further including a base member, a hollow support member in said water jacket movable on said base member, said combustion chamber being mounted on said support member, said support member maintaining said combustion chamber spaced from said shell and being formed with a plurality of openings for admitting water from said hollow support member to said water jacket.

4. In a furnace, in combination, an elongated horizontal combustion chamber; an outer shell substantially coextensive with and surrounding said chamber, said shell forming a water jacket with said chamber and said shell being spaced at all parts from said chambers; an elongated channel member extending longitudinally along the bottom of said combustion chamber and supporting the latter, said channel member having side walls extending downwardly from said combustion chamber to said shell and said channel member extending along the entire length of said shell and said combustion chamber, said side walls being formed with openings passing therethrough; and conduit means communicating with the interior of said channel members for supplying a liquid to the interior thereof to flow through said openings into said jacket, whereby said channel member in addition to serving as a support for said combustion chamber in said shell also serves to distribute water into the water jacket.

5. In a furnace, in combination, an elongated cylindrical combustion chamber having a horizontal longitudinal axis and two end walls extending transversely of said axis; a shell surrounding said combustion chamber and forming a Water jacket therewith; burner means communicating with said combustion chamber at one of the end walls thereof at a part of said one end wall spaced from said axis for projecting a flame into said combustion chamber longitudinally thereof, said burner means during operation providing an endless stream of combustion materials circulating in said chamber; and a tire tube in said water jacket extending parallel to said axis and communicating with said combustion chamber adjacent said one end wall thereof at a part spaced from said burner means on the side of said axis opposite from said burner means, said tube providing restricted outlet means for discharging only a portion of said combustion materials from said stream out of said chamber, whereby another potrion of said materials returns to said stream, said one end wall of said combustion chamber being in the form of a lire door and said door being formed with a duct providing communication between the interior of said chamber and said re tube so that gases flow from the interior of said chamber through said duct of said fire door to said fire tube.

6. A iiuid heater including a lire box formed by a substantially cylindrical shell having a length greater than its diameter and having an end back wall, a closure forming an end front wall for said enclosure, lluid fuel burner means mounted through said closure at a location between il s the axis of said shell and its periphery and directing a flow of burning uid fuel and gas flowing backwardly towards said back wall mainly on one side of this axis and whichis looped forwardly from the back wall and Q flows forwardly mainly on the opposite side of this axis, a jacket enclosure for said shell and its back Wall for surrounding the latter and the shell' with the uid to be v heated, and ilue means having an entrance at leas-t adjacent to said end front wall and communicating with the shells interior and having an exhaust exit for connection with the outer atmosphere, the total flow capacity of said flue means being related to the capacity of said burner to form hot gases from said burning iiuid `fuel within Y said re box, to maintain a superatrnospheric pressure within the lire box; said pressure causing a portion of said forward flow to join with said backward flow to form a whirling closed loop of burning fluid fuel and gas within said lire box, said burner means introducing said flow substantially directly into the end of said shell at a location at least adjacent toV said front end wall and causing said closed loop to substantially entirely fill said iire box. Y

7. A fluid heater including a fire box formed by a substantially cylindrical shell having a length greater than its diameter and having an end back wall, a closure forming an end front wall for said enclosure, fiuid fuel burner means mounted through said closure at a location between the axis of said shell and its periphery and directing v a flow of burning fluid fuel and gas flowing backwardly towards said back wall mainly on one side of this axis and which is looped forwardly from the back wall and flows forwardly mainly on the opposite side of this axis, a jacket enclosure for said shell and its back wall for surrounding the latter and the shell withV the iiuid to be heated', and flue means having an entrance at least adjacent to said end front wall and communicating with the j shells interior and having an exhaust exit for connection with the outer atmosphere, the total fiow capacity of said flue means being related to the capacity of said burnerV to form hot gases from Said burning fluid fuel within said re box, to maintain a superatrnospheric pressure within the lire box; said liue means including at least one-due tube extending through said' jacket enclosure for substantially the length of said shell, at least a portion of Y the inner surface of said end front wall forming a space extending from said shell and connecting with the end of said flue tube adjacent to the end front Wall to formV entrance to the flue means.

8. A duid heater including a re box formed by a substantially cylindrical shell having av length greater thany its diameter and having an end back wall, a closure forming an end front wall for `said enclosure, fluid fuel burner means mounted through said Vclosure yat a location between the axis of said shell and its periphery and directing a flow of burning fluid fuel and gas flowing Vbackwardly towards said back wall mainly on one side of this axis and which is looped forwardly from the back wall and ows forwardly mainly on the opposite side of this axis, a jacket enclosure for said shell and its back wall for surrounding the latter and the shell-with the uid to bevheated, and flue rneans'having an entrance at least adjacent to said end front wall and communicating with the shells interior and having an exhaust exit for connection with the outer atmosphere, the total flow capacity of said line means being related to the` capacity of substantially cylindrical shellv having a length greater than its diameter and having an end back wall, a closure forming an end front wall for said enclosure, fluid fuel burner means mounted through said closure at a location between the axis of said shell and its periphery and directing a flow of burning uid fuel and gas flowing backwardly towards said back wall mainly on one side of this axis and which is looped forwardly from the back Wall and flowsV forwardly mainly on the opposite side of this axis, a jacket enclosure for said shell and its back wall for surrounding the latter'l and the-shell with the fluid to be heated, and flue means having an entrance Vat least adjacent to said end front wall and communicating with the shells interior'andhaving an exhaust exit for connection with the outer atmosphere, the total flow capacity of said flue means lbeing related to the capacity of said burner to form hotgases from said burning fluid fuel within said fire box, to maintain a superatmospheric pressure within the fire box; said pressure causing a portion of said forward flow to join with said backward flow to form a whirling closed loop of burning fluid fuel and gas-within said lire box, said burner means introducing said flow substantially directly into the end of vsaid shell at a location adjacent to said front end wall and causing said "'closed; loop to substantially entirely till said lire box; said flue means including at least one flue tube extending through said jacket enclosure for substantially the length of said shell, at least a portion of the inner surface of said end front wall forming a space extending from said shell and connecting with ythe end of said liuc tube adjacent to the end front wall to form said entrance to the flue means.

10. A fluid heater including a fire box formed by a substantially cylindrical shell having a length greater than its diameter and having an end back Wall, a closure forming an end front wall for said enclosure, lluid fuel burner means mounted through said closure at a location between the axis of said shell and its periphery and directing a flow of burning fluid fuel and gasflowing backwardly towards said back wall mainly on one side of this axis and which is looped forwardly from the back wall and flows forwardly mainly on the opposite side .of this axis, a jacket enclosure for saidshell and its back wall for surrounding the latter and the. shell with the fluid to be heated, and flue means having an entrance at least adjacent to said-end front wall and communicating with the shells interior and having an exhaustexit for connection with the outer atmosphere, the total flow capacity of said line means being related to the capacity of said burner to form hot gases from said burning fluid fuel within said tire box, to maintain a superatmospheric pressure within the fire box; said pressure causing a portion of said forward flow to join with said backward liow to form a whirling closed loop of burning fluid fuel and gas within said fire box, said burner means introducing said flow substantially directly into the end of said shellrat a location adjacent to said front end wall and causing said closed loop to substantially entirely fill said fire box; the inner surface of at least said end back said burner to form hot gases from said burningiluid wall being substantially concave and reducing the flow resistance to said whirling* closed loop.

11A duid heater including a fire box formed by a substantially cylindrical shell having a length greater than `its diameter and having an end back wall, a closure forming an end front Iwall for said enclosure, fluid fuel burner means mounted through said closure at a location between the axis of said shell and its periphery and directing a flow of burning fluid fuel`- and gas flowing backwardly ltowards said back wall mainly on one side of this axis and which is looped forwardly from the back wall'and flows forwardly mainly on the opposite side of this axis, a jacket enclosure for said shell and its back'rwall for surroundingthe latter andthe shell with Vthe fluid to be heated, and ue means having an entrance at least adjacent tosaid end front wall and communicating with the shells interior and having an exhaust exit for connection with the outer atmosphere, the total flow capacity of said flue means being related to the capacity of said burner to form hot gases from said burning iuid fuel Within said fire box, to maintain a superatmospheric pressure within the fire box; said pressure causing a portion of said for-ward flow to join wtih said backward flow to form a whirling closed loop of burning fluid fuel and gas within said lire box, said burner means introducing said flow substantially directly into the end of said shell at a location adjacent to said front end wall and causing said closed loop to substantially entirely lill said lire box; the inner surface of said end back wall being substantially concave, said ue means including a plurality of flue tubes extending through said jacket enclosure for the length of said shell, said end front wall having a concave inner surface open to said shell and to the ends of the llue tubes adjacent thereto and forming said entrance to said flue means, said concave surfaces reducing the flow resistance to said whirling closed loop of burning fluid fuel and gas.

l2. A fluid heater including a fire box formed by a substantially cylindrical shell having a length greater than its diameter and having an end back wall, a closure forming an end front wall for said enclosure, fluid fuel burner means mounted through said closure at a location between the axis of said shell and its periphery and directing a flow of burning uid fuel and gas flowing backwardly towards said back wall mainly on one side of this axis and which is looped forwardly from the back wall and flows forwardly mainly on the opposite side of this axis, a jacket enclosure for said shell and its back wall for surrounding the latter and the shell with the fluid to be heated, and flue means having an entrance at least adjacent to said end front wall and communicating with the shells interior and having an exhaust exit for connection with the outer atmosphere, the total flow capacity of said flue means being related to the capacity of said burner to form hot gases from said burning fluid fuel within said fire box, to maintain a superatmospheric pressure Within the fire box; said pressure causing a portion of said forward flow to join with said backward flow to form a whirling closed loop of burning fluid fuel and gas within said fire box, said burner means introducing said flow substantially directly into the end of said shell at a location adjacent to said front end wall and causing said closed loop to substantially entirely fill said fire box; said closure forming said end front Wall being hollow, and means for conducting fluid from said jacket enclosure through said hollow closure.

13. A fluid heater including a re box formed by a susbtantially cylindrical shell having a length greater than its diameter and having an end back wall, a closure forming an end front wall for said enclosure, uid fuel burner means mounted through said closure at a location between the axis of said shell and its periphery and directing a flow of burning uid fuel and gas flowing backwardly towards said back wall mainly on one side of this axis and which is looped forwardly from the back wall and flows forwardly mainly on the opposite side of this axis, a jacket enclosure for said shell and its back wall for surrounding the latter and the shell with the fluid to be heated, and flue means having an entrance at least adjacent to said end front wall and communicating with the shells interior and having an exhaust exist for connection with the outer atmosphere, the total flow capacity of said flue means being related to the capacity of said burner to form hot gases from said burning fluid fuel within said fire box, to maintain a superatmospheric pressure within the re box; said pressure causing a portion of said forward flow to join with said backward ow to form a whirling closed loop of burning liuid fuel and gas within said fire box, said burner means introducing said ow substantially directly Iinto the end of said shell at a location adjacent to said front end wall and causing said closed loop to substantially entirely lill said fire box; the inner surface of said end back wall being substantially concave, said ue means including a plural-ity of flue tubes extending through said jacket enclosure for the length of said shell, said end front wall having a concave inner surface open to said shell and to the ends of the ue tubes adjacent thereto and forming said entrance to said ue means, said concave surfaces reducing the ow resistance to said whirling closed loop of burning fluid fuel and gas; said closure forming said end front wall being hollow, and means for conducting fluid from said jacket enclosure through said hollow closure.

References Cited by the Examiner UNITED STATES PATENTS 406,753 7/89 Mason 110-28 961,672 6/10 Barnhurst 110-28 1,992,794 2/ 35 Woodruff 122-182 2,674,981 4/54 Clarkson 122--136 PERCY L. PATRICK, Primary Examiner.

KENNETH W. SPRAGUE, Examiner.

UNITED STATES PATENT FFICE CERTIFICATE 0F CRRECTION Patent No. 3,171,388 A March 2, 1965 Felix Ganz It is hereby certified that error appears ini-the above numbered patent reqiiring correction and that the said Letters Patent should read as Corrected, below Column 1, line 4Z, for "exists" readexits line 48 for "undersired" read undesired column 2, line 45,l for "PTOVdQS" read provides Column 5, line 11, for "f11ue"`read flue line 69,"af'ter "that" insert even column 6, line 6, for "existing" read exiting -';A Column 6, line 28, for "cavity" read concavit'y column l0, line 64, for "potrion" read "portion Column 11,- line 48, before "entrance" insert said column .14,1ine 1'5, for "exist" read exit Signed and sealed this 417th day ofv August 1965 (SEAL) Attest:

ERNEST w. swIDER EDWARD J. BRENNER -Allcsting Officer Commissioner of Patents 

1. A FLUID HEATER INCLUDING A FIRE BOX FORMED BY A SUBSTANTIALLY CYLINDRICAL SHELL HAVING A LENGTH GREATER THAN ITS DIAMETER AND HAVING AN END BACK WALL, A CLOSURE FORMING AN END FRONT WALL FOR SAID ENCLOSURE, FLUID FUEL BURNER MEANS MOUNTED THROUGH SAID CLOSURE AT A LOCATION BETWEEN THE AXIS OF SAID SHELL AND ITS PERIPHERY AND DIRECTING A FLOW OF BURNING FLUID FUEL AND GAS FLOWING BACKWARDLY TOWARDS SAID BACK WALL MAINLY ON ONE SIDE OF THIS AXIS AND WHICH IS LOOPED FORWARDLY FROM THE BACK WALL AND FLOWS FORWARDLY MAINLY ON THE OPPOSITE SIDE OF THIS AXIS, A JACKET ENCLOSURE FOR SAID SHELL AND ITS BACK WALL FOR SURROUNDING THE LATTER AND THE SHELL WITH THE FLUID TO BE HEATED, AND FLUE MEANS HAVING AN ENTRANCE AT LEAST ADJACENT TO SAID END FRONT WALL AND COMMUNICATING WITH THE SHELL''S INTERIOR AND HAVING AN EXHAUST EXIT FOR CONNECTION WITH THE OUTER ATMOSPHERE, THE TOTAL FLOW CAPACITY OF SAID FLUE MEANS BEING RELATED TO THE CAPACITY OF SAID BURNER TO FORM HOT GASES FROM SAID BURNING FLUID FUEL WITHIN SAID FIRE BOX, TO MAINTAIN THE SUPERATMOSPHERIC PRESSURE WITHIN THE FIRE BOX. 